British number one Dan Evans saw four match points slip by as he lost 6-4 6-7 (7-9) 6-4 to Ugo Humbert of France in the European Open semi-finals.
It was the third three-set match of the week for world number 35 Evans, seeking his first ATP Tour title.
In his first meeting with French left-hander Humbert, ranked 38, Evans was beaten in three hours 12 minutes.
Humbert, 22, faces Alex de Minaur in Sunday's final after the Australian beat fourth seed Grigor Dimitrov.
De Minaur, 21, captured three titles last year and defeated world number 20 and eight-time ATP title winner Dimitrov 7-6 (7-4) 6-7 (3-7) 6-4 in two hours 48 minutes.
Humbert, who claimed his maiden ATP title in Auckland in January, trailed 6-3 in the second set tie-break to 30-year-old Evans - but whittled that advantage away.
The Briton, beaten in ATP finals at Sydney in 2017 and Delray Beach last year, broke Humbert and had another chance to serve for the match.
But Evans, who saved a match point and beat third seed Karen Khachanov less than 24 hours earlier, was again denied and was broken by Humbert at the start of the decider.
He failed to grasp two break-point opportunities to make it 4-4 and another for 5-5, which allowed the French player the chance to serve out, winning on his third match point.
"The start of the match wasn't easy as he didn't give me much pace and suddenly he accelerated," said Humbert. "I need to find a solution and came to the net more.
"I was four match points down, but I was mentally strong and I took my opportunities. I remained aggressive and when I won the second set, I knew I'd regained the momentum."